Journal of Dental Research, Vol 71, 438-442, Copyright © 1992 by International & American Associations for Dental Research Online Journals
Measurement of water sorption by resin composite adhesives with near-infrared spectroscopy
A. M. Diaz-Arnold, M. A. Arnold and V. D. Williams
Department of Family Dentistry, College of Dentistry, University of Iowa, Iowa City 52242.
Spectroscopic methodology was used to follow the water uptake of disks of
two resin composite luting agents during long-term storage.
Fourier-transform near-infrared (FT-NIR) spectroscopy was used for
collection of spectra over the 4200-6500 cm-1 spectral region. The
5200-cm-1 absorption band of water was monitored initially, at 24 h, seven
days, two weeks, and then monthly over a period of 12 months. The disks
were stored in water, air, and desiccated conditions. Disks were also
subjected to two alternate cycles (two weeks each) of hydration and
desiccation. A spectral manipulation program was used for quantitation of
the area under the water absorbance band. Area ratios demonstrated similar
water-uptake patterns for the two adhesives. Rapid water uptake was seen
within the first two weeks of storage. Alternate hydration and desiccation
of the samples showed that water uptake by the filler/polymer network was
partially reversible. The desiccant was unable to remove all the water from
the samples, which indicated that some water was tightly held within the
sample matrix. FT-NIR spectroscopy is recommended as an effective method
for study of the equilibration of resin composites in water.
